Pablo Manzano

Extreme long-distance seed dispersal via sheep

Extremely long seed dispersal distances occur as a result of processes such as ocean drift and tornadoes. However, we have found that large numbers of seeds with different morphologies (Trifolium angustifolium, Daucus carota, Hordeum murinum, and Plantago lagopus) are frequently dispersed equivalent distances while attached to migrating ungulates. We determined experimentally that seeds attached to the fleece of traditional nomadic (“transhumant”) sheep are transported distances of up to several hundred kilometers in substantial numbers (ranging from 5–47% of the initial seed population). Given the current and historical importance of migrating herds of sheep (wild and domestic) on different continents, the results of this study highlight the role of adhesion in long-distance dispersal and support the inclusion of migrating ungulates among forces responsible rapid plant migrations (eg following glaciations, invasion events, or in a future global change scenario). Our results also highlight an unexplored ecological consequence of abandoning nomadism.

Sheep gut passage and survival of Mediterranean shrub seeds

Although viable seeds of Mediterranean dry-fruited shrubs are found in herbivore dung, the ecological importance of this observation is still not well understood. We analysed seed retrieval percentages, defecation time and germinability after sheep gut passage for the five most common shrub species of an area in central Spain ( Retama sphaerocarpa , Cytisus scoparius , Halimium umbellatum subsp. viscosum , Cistus ladanifer and Lavandula stoechas subsp. pedunculata ). Five ewes were fed seeds, and their dung was collected regularly during the following week. Seeds were hand-sorted from dung subsamples and tested for germinability. The defecated seeds were clustered in time, with a majority retrieved in the 24–40 h period, although over 1% of the seeds were retained in the gut for more than 72 h. Data suggested a possible link between seed size and retrieval, with medium-sized seeds less damaged (16–23%) than larger and smaller seeds (10–12%), although only a small number of species were studied. Germination results showed an increased percentage of germination after gut passage for H. umbellatum (x 2 test, P C. scoparius ( P L. stoechas did not germinate after gut passage. The results indicate a potential role of herbivore endozoochory for the long-distance dispersal of dry-fruited shrubs and their potential colonization of distant sites.

Policies in support of pastoralism and biodiversity in the heterogeneous drylands of East Africa

Research and practice are increasingly demonstrating the environmental benefits of pastoralism and the opportunity for sustainable development of pastoral communities through a combination of livestock and biodiversity-related business. To take full advantage of the potential biodiversity-pastoral synergies, it will be crucial to put in place supporting policies. They need to be embedded in the context of overall pastoral development. However, rangelands and pastoral societies in drylands are heterogeneous, and development options cannot be assumed to be uniform. Factors such as aridity, access to markets and population pressure influence the constraints and the opportunities for both pastoral and non-pastoral communities. We describe the differential challenges to development along these gradients and identify investment priorities if the policy objectives were to support the complementarities between pastoralism and biodiversity conservation.

Plant community assembly in Mediterranean grasslands: understanding the interplay between grazing and spatio-temporal water availability

Rota, C. (corresponding author, cristina.rota@uam.es), Manzano, P. (pablo.manzano.baena@gmail.com), Carmona, C.P. (perezcarmonacarlos@gmail.com), Malo, J.E. (je.malo@uam.es), Peco, B. (begonna.peco@uam.es) Terrestrial Ecology Group, Department of Ecology, Autonomous University of Madrid, Madrid 28049, Spain; Department of Botany, Faculty of Science, University of South Bohemia, Cesk e Bud ejovice 37005, Czech Republic Abstract

Testing seed-size predictions in Mediterranean annual grasslands

On the basis of previous research, we predict that Mediterranean grasslands should show larger-seeded annuals in: (1) more-arid grasslands; (2) more-fertile soils; (3) less-grazed grasslands; and (4) grasslands with lower intensities of seed predation by ants. To test these predictions, we set 29 sampling units of 50m £ 50m in a 1000km 2 grassland area in Central Spain, and characterized them according to the former factors. We then recorded annual vegetation using ten quadrats of 20cm £ 20cm in each sampling unit. Seed size at the community level was described using six variables: (1) mean seed mass; (2) standard deviation of seed mass; (3) weighted mean seed mass (by species frequencies); (4) proportion of small-seeded annuals; (5) proportion of medium-seeded annuals; and (6) proportion of large-seeded annuals. Most climate variables (mean annual temperature, length of the summer drought, water balance and mean annual precipitation) correlated with seed-size descriptors, showing that large-seeded annuals increase in warmer and more-arid communities. Mean seed size was modelled as a function of mean annual temperature and grazing pressure. According to this model, warmer and less-grazed communities tend to show a smaller mean seed size. These results confirm the importance of seed-size descriptors at the community level in Mediterranean grasslands, and the role of climate and grazing as major drivers in these communities. Conversely, hypotheses about soil fertility and seed predation by ants were not supported by our results.

Towards Integrated Understanding of the Rhizosphere Phenomenon as Ecological Driver: Can Rhizoculture Improve Agricultural and Forestry Systems?

Agriculture and forestry traditionally focus on improving plant growth traits based on an anthropocentric point of view. This paradigm has led to global problems associated to soil overexploitation such as soil losses, reductions of the C stock in soils, and the generalized use of fertilizers, which particularly increases the costs of production and pollution treatment. This view may also have limited our understanding of mutualistic symbioses of plants and microorganisms assuming that the main role of non-photosynthetic symbionts is to mobilize the nutrients that are necessary for plant growth and development, and being plants the dominant agents of the symbiotic relationship. In response to these issues, this chapter offers an alternative approach taking advantage of the “rhizo-centric” point of view, where non-photosynthetic partners are the main protagonists in play; and secondly, it builds a multidisciplinary body of knowledge that could be called “rhizoculture”, which includes techniques focussing on the intensification of the development and activity of roots, mycorrhizae, and other symbiotic and free living rhizosphere organisms. In short, rhizoculture may lead to decrease plant production dependence on fertilization and provides other benefits to agriculture, forestry, and the environment. Within this conceptual framework, the first objective of this book chapter is to explore whether there is a “paradox of calcium salts” (i.e., Ca2+ and its salts are simultaneously nutrients, promoters, and stressors for the host plants) that would explain a dominance of mycorrhizal fungi over plants based on inducing a Ca(pH)–mediated chlorosis to the host plants. If this paradigm shifting hypothesis were finally fully verified, it would provide conceptual bases to reconsider our current technologies in agriculture and forestry by introducing the “rhizocultural” approach, based on the management of roots (introducing alternative cultural practices), Ca2+ salts (using liming and other techniques), rock-eating mycorrhizae, organic matter, and the soil microbiome (increasing the presence of symbiotic microorganisms against saprophytes), N and P contents (by aquaculture and smart recycling of organic waste), and the physical properties of the soil (by the activity of soil symbiotic microorganisms and soil fauna, such as ants, termites and earthworms). The development of such new technological approaches in rhizoculture would significantly decrease the high cost and associated pollution of the application of fertilizers and phytochemicals; as well as it would increase soil C stocks, improve the resilience of agricultural and forest systems to environmental disturbances, such as climate change, and enhance food production and security.